JPS6114510A - Ultrasonic thickness gauge - Google Patents

Abstract

PURPOSE:To measure a thickness correctly and easily by arranging plural ultrasonic vibrators with division in peripheral direction and by finding the differential time with receipt of the echo that the ultrasonic wave transmitted by each vibrator is reflected on the surface and backface of a tube. CONSTITUTION: The bottom face of a probe 11 arranging ultrasonic vibrators U1-U8 is placed on the tube to be measured. Then, by the command sent from a control circuit 13 the vibrator U1 is connected to an echo sounder transducer 14 via a multiplexer 12 and a voltage is applied on the vibrator U1 from the echo sounder transducer 14, and an ultrasonic wave is irradiated with the excitation of the U1. A gate 15 is then opened only for the period that the two wave receiving signals reflected on the surface and backface of the tube are inputted into the gate circuit 15, and during the period thereof the clock signal transmitted from a clock signal generator 16 is inputted into an arithmetic circuit 17. The thickness of the tube is then calculated from the differential time of two wave receiving signals found from the number of clock signals and the sound speed value of a sound speed measuring part 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an ultrasonic thickness needle used for measuring the thickness of tubes, etc.

(B) Conventional technology As shown in FIG. 3, an ultrasonic thickness gauge transmits a pulse signal (see FIG. ) to vibrate the ultrasonic transducer, project this ultrasonic sound (see Figure 4) onto the tube 4, and receive the signal reflected from the outer surface A and inner surface B of the tube 4. , the thickness of the tube 4 is calculated from the time difference T between these received signals (see FIG. 4C) and the preset sound velocity. In this type of ultrasonic thickness gage, the ultrasonic transducer of the probe is divided into two parts, and when measuring the thickness of the pipe, the split axis of the transducer is set in the longitudinal direction of the pipe and perpendicular to it. There is a device in which the smaller value of the measured thickness is obtained as the thickness. However, with this ultrasonic thickness gauge, a special jig 5 (third
(see figure) had to be used. Another drawback is that different jigs are required depending on the diameter of the tube in order to obtain an optimal contact state between the tube and the probe.

(c) Purpose In view of the above, it is an object of the present invention to provide an ultrasonic thickness gauge that allows anyone to easily perform accurate measurements without using a special jig.

(D) Structure In order to achieve the above object, the ultrasonic thickness gauge of the present invention includes a probe in which a plurality of ultrasonic transducers are arranged divided in the circumferential direction, a transducer, and the ultrasonic transducer. a scanning means that is coupled to the transducer in a time-sequential manner and drives each ultrasonic transducer in a time-division manner, and a time difference between signals transmitted from the transducer for each allocated divided time of each ultrasonic transducer; a time difference calculation means for calculating the thickness, a thickness calculation means for calculating the thickness from the calculated time difference and the speed of sound, a storage means for storing the minimum value of the calculated thickness, and a thickness stored in the storage means. and an output means for outputting.

In this ultrasonic thickness gauge, when a plurality of ultrasonic transducers are time-divisionally driven, the thickness is calculated for each allocated divided time of each ultrasonic transducer. Each ultrasonic transducer is arranged in the circumferential direction, and each division axis faces each direction including the longitudinal direction of the tube and the vertical direction thereof. Therefore, by finding the minimum value of the thickness calculated for each division time of each ultrasonic transducer without moving the probe, it is possible to obtain equivalent results by moving the probe in each direction and measuring the minimum value. can get.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 1 is a block diagram of an ultrasonic thickness gauge showing one embodiment of the present invention. In the same figure, inside the probe 11, there are 8
divided ultrasonic transducers U1, U2,..., U8
is provided. These ultrasonic transducers U1, U2,
. . , U8 is arranged in the circumferential direction of the probe 11, as shown in the bottom view of the probe J1 in FIG. 2, and its division axis is radial. However, the number of divisions can be selected to any value other than 8, and the shape of the bottom surface of the probe 11 is not limited to a circle.

Each ultrasonic transducer U1.1. J2, .

The transducer 14 outputs a pulse signal in response to a command signal e from the control circuit 13, receives an echo (received signal) from the probe 11, and inputs this received signal to the gate circuit 15. ing.

The gate circuit 15 is opened during the period when the received signal from the first sales outlet and the received signal from the second sales outlet are input, and during this period, the clock signal from the clock signal generator 16 is input to the arithmetic circuit 17.
is input. Based on this number of clock signals, the time difference between the first selling point and the second selling point is calculated.

The arithmetic circuit 17 has the function of calculating the thickness from the number of clock signals from the gate circuit 15, that is, the time difference T, and the sound speed set by the sound speed setting section 18, in response to the command signal g from the control circuit 13, It has a function to calculate the minimum thickness up to that point for each scan.

The memory 19 is provided to store the minimum thickness value calculated by the arithmetic circuit 17, and the display unit 20 displays the minimum thickness value stored in the memory 20. .

Next, a method and operation for measuring the thickness of a pipe using the ultrasonic thickness gauge according to the embodiment configured as described above will be explained.

During measurement, the bottom surface of the probe 11 is placed on the tube to be measured. Then, in response to the signal d from the control circuit 13, the ultrasonic transducer U1 is first connected to the transducer 14 via the multiplexer 12. Then, a pulse voltage is applied from the transducer 14 to the ultrasonic transducer U1 to excite it. The ultrasonic waves emitted from the ultrasonic transducer U1 are reflected on the front and back surfaces of the tube and return to the transducer 14 as echoes. The gate 15 is opened only during the period when the received signals of these two echoes are input to the gate circuit 15, and during this period, the clock signal is transmitted to the clock signal generator 16 and the gate circuit 15.
The clock signal is then input to the arithmetic circuit 17, and the arithmetic circuit 17 counts this clock signal to find the time IT of the first and second received signals. On the other hand, since the sound speed value C is set in the sound speed setting section 18, the arithmetic circuit 17
The thickness of the tube is calculated from the time difference T between the received signals and the sound velocity value C. This thickness is then stored in memory 19.

When a series of thickness measurement processes regarding the ultrasonic transducer U1 are completed in the manner described above, the control circuit 13 sends a scanning signal to the multiplexer 12, and by switching, the ultrasonic transducer U2 becomes a transducer. Connect to 14. Then, the thickness of the tube is determined in the same manner as in the case of the ultrasonic transducer U1. Also, the obtained tube thickness is compared with the previous tube thickness, and the smaller value is stored in the memory 19.

Thereafter, in the same manner, the multiplexer 12 is switched every time the time passes, and the ultrasonic transducers U2, U3, . . . , U8 are switched.
are connected to the transducer 14 in time order, the current measured value and the previous minimum value are compared, and the smaller value is stored in the memory 19 as the new minimum value.

When the processing scan for the ultrasonic transducers 1, U2, . . . , U8 is completed, the smallest numerical value in the memory 19 is displayed on the display unit 20 as the measured thickness.

Note that the data in the memory 19 is set to the maximum value by a signal from the control circuit 13 before the start of scanning.

In the above embodiment, the minimum thickness value is determined for each division time, and this is stored in the memory 20, and the minimum thickness value is updated for each division time. Alternatively, the one with the smallest time difference may be stored in the memory 20, the minimum value of the thickness may be calculated from the smallest time difference and the speed of sound, and this minimum value may be displayed on the display section 20. good.

(f) Effects According to this invention, the minimum value of thickness can be determined without moving the probe in any way, and not only does it require no special jig to measure thickness, but it also makes measurement very easy. It can be done.

[Brief explanation of the drawing]

FIG. 1 shows an ultrasonic wave thickness illustrating one embodiment of the present invention.
, a block diagram of the thickness gauge, FIG. 2 is a bottom view of the probe used in the same embodiment, FIG. 3 is a schematic diagram for explaining the principle of a conventional general ultrasonic thickness needle, and FIG. Figure 4 is the same waveform diagram. 11 nib lobe, 12: multiplexer, 13: control circuit, 14: transducer, 15: gate circuit, 16: clock signal generator, 17:
Arithmetic circuit, 18: Sound speed setting section, 19: Memory, 2
0: Display section,

Claims (1)

[Claims] (1) A probe in which a plurality of ultrasonic transducers are dividedly arranged in the circumferential direction, a transducer, and each ultrasonic transducer is switched in time order and coupled to the transducer, and each ultrasonic transducer is connected to the transducer. scanning means for time-divisionally driving the ultrasonic transducer; time difference calculating means for calculating the time difference between the signals transmitted from the transducer for each allocated divided time of each ultrasonic transducer; An ultrasonic thickness gage comprising: a thickness calculation means for calculating the minimum value of the calculated thickness; a storage means for storing the minimum value of the calculated thickness; and an output means for outputting the thickness stored in the storage means.